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C. H. SMOOT' CENTRALIZED REGULATION Dec. 21 192s.

4'Sheets-Sheet 1 Filed Nov. 8

W/T/VESSfQ Q I V INVENTO v N JLZMQWZZMI C. H. SMOOT CENTRALIZED REGULATION Dec. 21 1926.

4 Sheets-Sheet 2 Original F'iled Novs. 1923 INVENTOR M H "AM BY as C. H. SMOOT CENTQRALIZED REGULATION Dec. 21 1926.

5 t 6 e h s s t e e h s 4 Original Filed 8. 1925 W/T/VESSES INVENTOR W H. W

BY v v (B q TI 5 C.H.SMOOT 21 1926- CENTBALIZED REGULATION R 1&507

4 sheets-sheet 4 Rein sued Dec. 21 1926.

NITED. STATES Re. 16,501 IPA-TENT OFFICE...

cnannns a. silicone! MAPLEWOOD, new assent.

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Original No. 1,651,272, dated August 25, 1915, Serial No. 873.531, filed- November 8, 1928. Application for reissue flied October-21, 1926. Serial No. 143.809..

This invention has to do with plants where a plurality of variable elements affecting the output require regulation not only 0 the aggregate of the output but also as to the various' proportions of the entities involved therein.

The invention comprises a master regulator and a method of control for controlling from a distance or from a central point or station not only the total of the variable elements independently of tlie'ratios between the elements but also the proportions of the elements independently of the total.

There are many kinds of plants where it is necessary to keep up continuous control both of the amount and the proportions as' for example, steam generating plants, blast 'furnaces, chemical factories and the like.

It is customary in such plants to provide means for adjusting or controlling at least some and ofttimes all of the various elements enteringinto the product. I have found that great economy and increased general efliciency are obtainable by using means for bringing all the" localcontrols to a central point and there with a master controller provide means to regulate not only the apportionmcntof the variables entering into the-formation of the product but also means to regulate the total output without varying the apportionment. I

'Morespecifically my invention comprises means for connecting up the various controls having to do with the generation. of steam in a number of boilers, to a master controller, by proper intermediate communicating ducts between the master controller and the local controls. The master controller is intended to automatically take charge of the generation of steam and hold in proper col-elation all the elements having to do with such generation. It also is equipped with indicating devices whereby an operator at the master controller will have a visual oversight of the condition of every control and may at the master controller vary the ratio between the different elements influencing the steam generation. The operator may thus maintain a character of combustion to give the best boiler efliciency for all conditions of load. If this is obtained at 15% 00,, then the master regulator is set for this'value, and the control system suppliesthe proper amount of coal and airto the furnace for each boiler, to produce this condition. The system operates on a fixed variation in steam pressure between a maximum and a minimum value; for example, between 200 and 190 pounds.

The control equipment consists of one master controller designed to control any number of boilers; two auxiliary regulators -for each boiler, to control the volume of air given amount of fuel and air to the boiler furnaces with each change of load on the boilers. If the-load is increased,- the steam pressureclecreases. This decrease in pressure on the master controller causes the auxiliary regulator to speed up the stoker engine to feed the proper amountof coal to the boiler to care for the load. The speed of the forced-draft fan isincreased and the osition of the dampers adjusted automatically, so that the necessary volume of air is suppliedto burn the increased volume of coal to a predetermined percent CO If the load decreases on the boilers, the steam pressure increases. The efi'ect of this increase in pressure is transmitted through themaster controller to the auxiliary regulators and the volume of coal-and air is decreased to meet the new condition. Various indicating devices onthe master controller in direct communication with the individual controls or with the individual elements influencing the generation of steam give a com arative vision of the exact state of alling indicated.

Figure 2 is a vertical section of the local control governing the forced-draft fan.

Figure 3 is a vertical section of the local.

control governing the stoker engine and fuela Figure 4 is a front elevation,- and Figure 5 is a transverse vertical section-of the master controller.

Referring to Figure 1, the master control- 7 ler isshown at 1, and consists of a panel upon which is mounted a regulator 2, which is-connected to the steam header and is res nsive to the full pressure of the boiler. ere is also mounted on the master controller a multiple air valve 3. One end of thisi air valve has a chamber 4 communicating .through a restricted passage 5, with a source of compressed air represented by the pipe .6, The degree of restriction of thepassage 5 may be adjusted by'means of a screw valve 7. From the chamber 4, compressed air may escape in various ways. At- 8, I show one of a series of boiler furnaces with a steam header 9,'which is connected by pipe .10 to a chamber 11 in regulator 2, where the steam pressure operates against a diaphragm "12. Bearing down upon this diaphragm m,

a direction opposed to the steam pressure is a yoke 13, the force holding it down beingsupplied b springs 14, which in turn are an ported y yoke 15 on the'regulator. The yo e 18 0 tes against a lever 16, pivoted at 17 and held against the yoke by spring,

e'purpose of'the spring 18, see Fig. 4, is to limit the maximum pull on the lever. 16 in closing valve 19 on its seat. The levera of 16 may beadjusted by threaded portion" 16. In practice the lever 16 is connected by link 16" to a lever16 at 13" which is pivoted to the yoke 13 at 13" and provided. with astop 13".v The outer end of this lever 16 operates against a cup valve 19, which tends to restrict the escape of air from chamber 4 through opening 20. From the construction described, itwill be obvious thatasthe steam pressure increases, forcing up the diaphragm 11, the cup valve 19 will be lifted *further from its seat, "allowing more air to escape from chamber 4, thus reducing the pressure in said chamber. It will be further obvious thatthe variations in chamber 4 will be proportional to the va- .riations of steam pressure although in an inverse order, the air pressure decreasing as the steam pressure increases andvice versa.

For example, while the steampressure is decreasing from 200 to 190' pounds, the air pressure in chamber 4 may increase from practically zero to about two pounds. The air valve 3 is provided also with a series of other outlets as shown at 3', 3", 3, 3"",

h each one of which has a regulating screw 21, whereby the amount of air escaping past each valve may be nicely adjusted. Theair in passing the adjusting valves 21, enters a chamber 22, from which it escapes to the atmosphere through orifice 23, controlled by an adjusting valve 24., Each one of the chambers '22 base manometer or pressure 1 gauge attached as shown at 25. From each. chamber 22 a pipe leads to some one or other of the local controls, The pipe'2.6,. for ex- .ample extends to all the controls regulating the flue da er. The pipe 27 extends to all the contro s regulating the speed of the stoker engines. The pipe 28 extends to allithe controls regulating the forced-draft dampers. The pipe 29 leads to all the controls ofthe forced-draft fans. If the load is increased on the boiler, the steampressure decreases. This will allow diaphragm'12 and yoke 13 to drop a slight amount, this movement being very small. As the yoke 13 moves downward, the moveinentis transmitted to cup 19 and decreases the flow of air to atmosphere, causing the pressure in chamber 4 to build up and putt-ingthe regu lator in astateof eq uilibrium' again. This increase in air pressure in chamber 4 is transmitted to regulators on the stocker and forced-draft blower engines, bymeans of the conduits 2 7 and 29, causing them to speed up. This pressure is also transmittedto the regulators on the ir and draft dampers, by means of pipes 28 and 28, and causes themto open an amount to supply the necessary air to burn the increased volume of coal supplied to the furnace. A small dash pot 30 under cup 19, prevents it from chattering. Although have shownthe choke valve 19 as controlled by the steam pressure it is obvious that it may be controlled by hand as for exampleiby a screw 19".

I will now descri 1e my preferred means for local control of the various functions in a boiler furnace. These controls are all built on the same general lines as shown in Figures 2 and 3, the former being a control for regulating the speed'of theforced-draft engine and the latter a control for r'egulating'the speed of the stoker engine.

-Beferring to Figure 2, 32 may represent an engine, driving ,a blower 33, del vering air through duct 34 toa set of furnaces. From this duct, a by-pass 35 communicates with the upper half 36. of a diaphragm chamher, the lower half 37 of which opens to the atmosphere through pipe 38. The diaphragm 39 will, therefore, be res nsive'to pressure of air delivered by the b ower and will, through lever 40, bring pressureto bear through stem 41 on the lever 42. This lever is pivoted by means of a flexible 'strip of metal at 43 and carries a weight 44 at its outer end, while at 45 it articulates with avertical reciprocating rod 46, communicating withthe diaphragm 47, exposed on one side to atmospheric pressure and on the other .side to pressure from one of the. control valves of the master controller throu pipe 29. Steam at boiler pressureis admitted at 48 to chamber 49 at the bottom of the regulator and passes through the passage 50 to chamber 51 ab ove piston '52, having two parts, the lower one being jlargerthan the upper one. Steam alsovpasses through the throttling orifice 53 andup'into the chamber 54' on the under side of the larger piston.

The pressure in'chamber 54 is cont-rolled by the position of valve 55 which allows steam to'lea' kto atmosphere through pipe 6. The steam pressure on piston 52, in COHJlHlCtlOIl with the, other forces acting on the regula tor, puts the whole system in balance for any given condition. Assume in Figure 2 that an increase in load takes place on the boiler.

.This' increase in load causes the pressure above the loading diaphragm 47 on the mastercontroller to increase and cause it to move downward. The downward movement of i thisdiaphragm is transmitted; to valve through valve stem 57 As valve 55 closes, it caus'es the pressure in chaniber54 to incrase and give piston 52- an upward motion, which will move a lever 58, connected with the throttle valve .5 9 of the blower enginefin such a direction as to openthe same and a mit more steam, and thusincreas'e 1 the-speed of the blower. .The motion of the I piston '52 upward and the downward mo-- tioh of the diaphra 47 are taken care of ln dash, pot 60. his dash pot prevents sudden change in the motionof the va- ,riousv parts and any tendency for the regulator to by stem to the piston 52 and,the lever 58 and the piston of the dash pct 62 is conheated by rod 63 'tothe lever. 42. An adjusting screw 64 may be used to regulate a restricted or' cefrom the dash pot to adjust thea nount of its retarding effect.

When loading diaphragm 47 was moved downward, it causedthe left hand end of lever 42-, which is supported. pivotally at 43, to" move upward. This upward motion of lever 42 'is transmitted to diaphragm 39 7 through-lever 40. \Vhen the blower speeds up, the pressure is increased ,in'the air duct, and this pressure is transmitted to diaphragm 3 9'and causes diaphragm 39 to tend to move downward and overcome the upward thrust of lever 4:0 and again put'the regulator in estate-of balance. The parts-of the regulator are so proportioned that every definite change in pressure on the loading diaphragm 47 corres ondingto a definitechange in load on the boiler, causes a definite change in air pressure in the forced-draft duct. This changein air pressure. when transmitted todiapliragm 39; puts the regulator in balance, after conditions have been adjusted to care for the load on the boiler.

Referring to Figure 3, a stokcr engine indicatedat 65 has its speed controlled by. a

""thi'otti'ebd which in turn is under control of lever 58-, piston52, dash pot 60, bypass valve 55,'andother elements similar to those used for the control of the blower'engiue.

nt. The dash pct 60 is connected On the stoker en ine. an oil type' 'vernor is used in container 6 is connected to the engine shaft through gears and a belt. In this container is a disk 68 with radial veins on its top surface. This disk is connected to the. regulatorand is held stationary, by means of a stem 69. When the air pressure is increased on diaphragm 47 through air pressure coming through pipe 27 from the master controller in response to a decrease in boiler 'ressure, the stoker engine is caused to spec up, and the left hand end of arm 42 starts to place 0? the flyball' type. An oil move upward. lVhen the enginespeeds up,

the speed of the oil container on the governor is increased, and oil is caused, by centrifugal force, to flow out from under disk 68. This causesa reduction ofpremure 'under the stationary disk, which increasesthe downward force on lever 42 to overcome the motion caused by the air pressure on dia-. phragm 47. -"The chan e' diaphragm 47 anddis 68 again puts lever 42 and regulator in balance, when the stoker engine has reached a speed to supply an amount of coal to the furnace corresponding to the new load conditions ont-he boiler. a

The volume regulator 70 of thestoker air duct (Figure 1 operates similarly to that on in forces acting on the forced-'dra t'blower engine, as explained" for Figure 2'. "If the load increases on the boiler, thea'ir pressure-from the master controller isincreased on th'ed'oading diaphragm of'the volume regulator and causes it to o crate and open the damper. 'Opening t e damper, in conjunction with the increased pressure produced by the fan, causes'the air to have an increased velocity and changes the pressure differential between the Ventur'i tube 71 and the Pitottube 72. This change in pressure acting onthe control diaphragm puts the regulator in balance for the new lead conditions. The balance is obtained at will be su plied to the fuel to burn it tothe such a point that the correct amount of air percent C 2 set on the master regulator. The increased volume of coal and air to the furnace, to take care of the: increasedc load, increases the volume of gases up the stack. If the stack damper was not changed, the draft balance over the fire would be discreases on the boiler. the master regulator increases the pressure on the loading diaphragm of the draft regulator and causes it to o crate to open the damper and increase the raft. This changes thepressure in the boiler uptake, which pressure is communicated to the control diaphragm on the, regulator through pipe 74 and puts the regulator in balance when the damper has taken a position to give balanced draft over the fire.

The speed of the stoker engine and the turbed. This is taken care of by thedraft regulator 73 ,(Figurel); When the'load -i'nmg to the stokerspeed, and consequently the forced-draft blower-bears a definite relation to the steam pressure, increasing as the pressure decreases and decreasing asthe pressure increases. However, the air pressure under. the stokcrs is maintained by the damper regulators at a value that will suply'the volume of air to the fire correspondamount of the coal-delivered to the furnace.

As the thickness of the fire increases, the resistance to the passage of air increases, which will tend to slow up the air flow.

A slight slowing up of the air flow will reduce the difference of pressure between the Venturi tube 71 and the Pitot tube 7 2,-whieh change, acting on the regulator. opens the damper an amount to maintain the flowof ,air practicallyconstant. On the other hand,

if a. hole blows in the fire, the velocity of the air in the duct increases and produces an increased difference- 1n prwsure between the Venturi tube 71 and the Pitottube 72, and

causes the regulator to close the damper until the volume of air going to' the fire will corres 0nd to the stoker speed. \Vhat has been sai vregarding a hole in the fire alsoapplies to a fire that burns thin. In this case the resistance to the fiow of air is reduced, and its increased velocity causes the regulator to adjust the damper to allow the proper amount of air to the furnace.

Adjustment for the relation between draft, stbker speed, air volume and forced-draftfan speed are made'by' adjusting the valves isting between the various controls and consequently the condition of the differentgroups' of variables andthey therefore en'- able the engineer to observe any departure from normalcy. The ratio of the variables, for example the ratio of the air Volume to the stoker speed which is a measure of the CO may be read directly by the use of a diagonal scalesuch as shown at 75, see Figure 4. The right hand end of this scale may be raised or lowered by rod 76 until its inclination corresponds to the relative heights of the two columns it is desired to compare when the proportionality may be read off from the scale. At 77 I have shown a comparison group indicator having its individual indicators connected by conduits with the individual members of any .one group of the variables, in this case the stack flues, so as to indicate any abnormal condition of any stack pressure by a departure from alignment of the indicator thus involved. Simiflow of all of the boilers.

, same input.

larly indicators such as shown at 78 maybe grouped together on the master controller and may show by their alignment or their lack of alignment whether'the tem ratures existing in the stack flues or some ot er function of the group that should be uniform is normal or otherwise.

In the embodiment of my invention shown and described herein, I have indicated a fluid medium as a means of communication between the local and master controls and in 1 dicators. It will, however, be obvious to those familiar with the art herein. involved thatelectricity may be made use'of as such a'medium of communication and I there-tore use the word medium in its-broadest sense.

It will be understood from'the foregoing description, that Isdesign to bring to a central point the control of all the elements.

having to do with the output of a plant, thus doing away with the ersonal factor of the individual operators hat I have found militates so against the attainment of the highest efficiency. With the centralized control one skilled man may have general super-- vision for the whole plant and can instantly detect any departure from normal of any part thereof and instantl apply the proper means of -correction. he lndividual attendants 'of the boilers can have no such general knowledge and cannot be trusted to do the right thing with regard to the plant as awhole. As an instance of the value of this centralization: Suppose thata compari} son indicator at the central controller station shows a reduction in the steam flow of one of the boilers from the average steam feed shows uniformity, the forced draft shows, on the comparison indicator for forced draft, that thesame boiler has an increase inthe draft.- This would indicate a. hole in the fuel bed and instructions could be'sent with the chief operator to have the fire'corrected. I

With the general and local controls working properly all the boilers will get the The juxtaposed meters show the average or maximum output which can he obtained. Hence it will be apparent thatv -with the input so heldautomatically uniform by the controller, any variation shown on any of the-juxtaposed meters from the average of all the meters will indicate directly to the operator which boiler is at fault. Without the control insuring a uniform input, the deflection of any one meter from the average would mean nothing since the variation might be due to different muts.

While I have described my invention with particular reference to steam generation, it is in its broader feature's'applicable to any plant where a plurality of variables are to be controlled from a central. point.

While the fuelv ill) I claim: L The method of detecting an inefiicientfire in aplurality (if-interconnected boilers,

vwhich comprises automatically regulating 'theeupply to each boilero'f *a' fixed proportion of the total fuel, registering injuxta positional: a central point the condition of such regulation, and registering in juxtaposition like functions indicating the output of theboilers so as to show any departurexinthe output-of'one boiler rom the average output of all boilers.

Q. Themethod of detecting an ineflicierit fire in a plurality of interconnected boilers,

which comprises automatically regulating the supply to each boiler of a fixed proportion- 0 total'air, registering in juxtaposition at a central point the condition" of such regulation, and registering in juxtaposition like functions indicating the output of the boilers so'as to show any departure in the output of'one'boiler from the average output of all boilers.

3. The method of detecting an ineflieient fire in a plurality of interconnected boilers, which comprises automatically regulating the su-ply to each boiler of a fixed proportion 0 the total f uelcn'd air, registering injuxtaposition at a central point the conditionof such' regulation, and registering in juxtaposition like functions indicating the output of: the boilers so as to show any departure' in the output of one boilerfrom the average output of all boilers.

4. The method of detecting an ine-Iiicient fire in a plurality of interconnected boilers,

1 which comprises automatically regulating the supply to each boiler of a fixed proportion of the total fuel, registering in juxtaposition at a central point the condition of such regulation, and causing an intermediate medium to register in juxtaposition like functions: influencing the performance of the boilers so as to indicate any departure in the output of one boiler-from the average out- 1 put of an boilers;

\ 5. The method of detecting an inefficient fire in a plurality of interconnected boilers,

' output of one boiler from the which comprises automatically regulating the supply to each boiler of a fixed proportion'ofi the total air, registering inrjuxtaposition at a. central point the condition of such regulation, and causing an. intermediate medium to register in juxtaposition like functions influencing the'performance ofthe boilers so as to indicate any departure in the average output of all boilers.

6. The method of detecting an inefficient fire in a plurality of interconnected boilers, which comprises automatically regulating the supply to each boiler of a fixed proportion of the total fuel and air, registering in juxtaposition at a central point the condition of such regulation, and causing an inboilers, means for registering-in juxtaposi- I tion the fuel supply to each 'boileryand means for registering in juxtaposition like functions influencing the performaneeof the boilers so as to indicate any departurein i the output-of one'boiler from the average ou'tputof all'boilers. f

8. A master controller for steam boiler plants, comprising means for regulat' the supply of fixed proportionsof air to al the boilers, means for registering in juxtaposition theair supply to each boilezg'and means for registering in juxtaposition like functions influencing'the performance. of the boilers'so as ,:t,0 indicate anydeparture in the output of-Jone boiler from the average output of all-boilers. v

-9. A master controller for steam boiler plants, comprising means for regulatingthe supply of fixed proportions-of fuel and air to all'the boilers, and means for registering in'juxtaposition the fuel and air supply to each boiler, means for registering in junta position like functions influencing the performance of the boilers so as to indicate any departure in the out at of one boiler from the average outputo all boilers 10. In combination with a steam: generating plant having a plurality oi variable elements afl'ecting the generation of steam, each of said elements having an individual local control, a master controller comprising means for regulating an'auxiliary'medium,

a plurality of individualconduits connected with said regulating means, individualregulators on the master controller for controlling the force of the auxiliary medium trans mitted by said conduits, each of said conduits being connected to one of said local controls, and means at the master controller responsive to boiler pressure for controlling the force of saidauxiliary medium transmitted tovsaid individual regulators;

11. In combination with a steam generating plant having a plurality of" variable elements affecting the generation of steam, each of said elements having an individual local control,- a master "controller com rising means for regulating an auxiliary me ium in multiplied inverse ratio to the pressure of steam, a plurality of" individual conduits connected with said re ulating means, individual regulators on 1: ve master controller for controlling the force of the auxiliar medium transmitted by said conduits, eac .of said conduits being connected to one of said local controls, and' means at the master controller for controlling the force of said.

sive means for controlling independently'the supply offuel and of air, and means on the master controller for regulating said variables independently and proportionately. 13. A master controller for power plants,

comprisin a. pressure chamber communicating wit 1 a source of fluid under constant pressure, means responsive to boiler pressure controlling the pressure in said chamber, a plurality of secondary chambers individually in communication with the fluid pressure chamber, local controls for the power plant, conduits connecting the local controls individually to the secondary chambers and individual means for adjusting the pressure in each of'the secondary chambers. n

14. A master controller for power plants comprising means responsive to boiler pressure, a source of constant'fluid ressure, a fluid pressure chamber connecte with said source throu h a restricted orifice, a relief valve contro lin' the leakage from said chamber, and a justable means connecting the boiler responsive means-with the relief valve, secondary chambers communicating with the fluid pressure chamber and means forcontrolling the flowfrom said fluid pressure chamber to the secondary chambers and from the secondary chambers to the atmosphere.

'15. A master controller for power plants, comprising, a pressure chamber commumcating with a source of fluid pressure, means responsive to boiler pressure'controlling the pressure in said chamber a lunal-ity of secondary chambers individual y in communication with the fluid pressure chamber, local.

controls for the power plant conduits connecting the local controls individually to the secondary chambers, individual means for adjusting the pressure in each of the secondary chambers, and pressure" gages registering the pressure'in the individual chambers.

16; Amaster controller for power plants, comprising a pressure chamber communicating with'a' source of fluid pressure, means responsive toboiler pressure controlling the pressure insaid chamber, a lurality of secondary chambers individua y in communication with the fluid pressure chamber, local controls for thepower plant, conduits connectin the local controls individually to the secon ary chambers, juxtaposed resure gages registering the pressure in't e individual c ambers andjm'eans foradjusting such pressures.

17. Regulating apparatus for the continuous control of elements se arately contributlng to the output'of a p ant, comprising .in combination, a master controller, indi- .v1dual regulators forthe separate elements,

means at the master controller for producing a prime regulating force and for adjusting its value, independent connections from the master controller to each of the individual regulators to apply thereto a regulating force responsive to said rime regulatin force,

independently adjusting the force applied through each such connection.

18. In a plant comprising a plurality of similar units for the production of the same output, regulating apparatus for the controlof elements separate y contributing to the output of-each unit, comprising-in combination, a master controller, individual regulators for the separate elements, means at the master controller for producing a prime regulating force and for adjustin its value, independent connections from t e master output, regulating ap amtus for the'control' of elements separate y contributing to the output of each unit, comprisin' in combination, a master controller, individual ,reguxators for the separate elements at each unit, means atthe master controller for producing a prime regulating force, means also at the master controller for producing 'a plu rality of forces for the control of the indi-- vidual regulators, said forces being equal in number to the number of individual regulators at each'unit, means for controlling the regulators of like elements by the same one of said forces, means for transmitting each of said forces to the regulators to be-controlled by it, and means for controllin all of said forces by said prime regulating orce.

units for the production of the same'output. regulating apparatus for the control of eleof each unit, comprisin in combination, a master controller, individual regulators for the separate elements, means at the master controller for producing a prime regulating 20. In a plant comprising a plurality ofcontroller to each of the individual regu1a- 'ments separately contributing to the output I force which is a function of the output of the whole plant, means for manuallY ad-y justing the value of' said prime regu ing force, independent connections from the master controller to each of the individual regulators to apply thereto a regulating force responsive to' said prime regulating force, 7

75 and means also at he master contro ler for f and means also at the master controller for independently adjusting the force applied throu h each such connection.

' 21. In combination with a steam generating plant having a plurality of variable elements affecting the generation of steam each of said elements having an individual local control, a master controller comprising means for regulating an auxiliary medium, a plurality of individual transmission lines connected with said regulating means, individual re ulators on the master controller for control ing the force of the auxiliary medium transmitted by said lines, each of said lines being connected to one of said local controls, and means at the master controller responsive to boiler pressure for controlling the force .of said auxiliary medium transmitted to said individual regulators.

22. In combination with a steam generat ing plant having a plurality of variable elements affecting the generation of steam, each of said elements having an individual local control, a master controller comprising means for regulating an auxiliary medium in multiplied inverse ratio to the pressure of steam, a plurality of individual transmission lines connected with said regulating means, individual-regulators on the master controller for controlling the force of the auxiliary medium transmitted by said'lines, each of said lines being connected with one of said local controls, and means at the master controller for controlling the force of said auxiliary medium transmitted to said individual regulators.

23. A combustion control apparatus for boiler plants, including a'inaster controller comprising means for varying a regulating auxi iary medium in multiplied inverse ratio to the pressure of steam, means at the master controller for adjusting said ratio, local combustion regulators, a pluralit of independ- I ent transmission lines for sum medium connecting the master, controller with difl'erent ldcal regulators, and adjusting .means at the master controller for each of said transmisboiler plants, a master controller, means for producing atwthe master controller a control force which is a function of the steam generated, a plurality of individual regulators for each boiler, transmission lines in parallel from the master controller corresponding in number to the number of regulators at each furnace, and parallel transmission lines from each of the first mentioned transmission lines In testimonv whereof, I hav name to this specifications signed a my to the likeregulators at the different boilers. 

